<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
<html lang="en">
<head>
	<meta http-equiv="Content-Type" content="text/html;charset=UTF-8">
	<title>数字对象</title>
	<script type="text/javascript">
		res = Math.abs('-9');

		// alert(typeof(res));
		// 
		res = Math.round(1.5);

		res = Math.ceil(1.0000011);

		res = Math.floor(1.99);

		res = Math.round(Math.random()*100);


		res = Math.round(Math.random()*(30-20)+20);







		document.write(res);





	</script>
</head>
<body>
	
</body>
</html>